Lift disengager



Feb; 1o, 1959 W. J. CROSS, JR.. ET AL LIFT DISENGAGER 2 Sheets-.Sheet 2Filed Deo. 19, 1957 f s. E Z mi Nima f WwH @W m M a 1 z WMM@ Z 5 4. a0MM z 2;/ .f w, ANIM ,l C? 111111 United States Patent O iceN LIFTDISENGAGER Willis J. Cross, Jr., Media, and Albert Wesley Hoge,

Swarthmore, Pa., assignors to Houdry Process Corporation, Wilmington,Del., a corporation of Delaware Application December 19, 1957, SerialNo. 703,958

5 Claims. (Cl. 302--59) peripheral region of the disengaging zone.

Because of the frangible nature of the granular contact materialgenerally employed in such hydrocarbon conversion systems, one of theprincipal problems involved inthe disengagement of the solids from thelift gas is that of minimizing forceful impact of the solids against themetal surfaces of the disengager vessel and its internal structuralelements as well as against each other. Such particle-to-particle impactmay result from collisions between ascending solids in the discharginglift stream and descending solids which have already become disengagedfrom the lift gas and are falling to the bottom of the disengager.Additionalforceful impact may occur when the falling disengagedparticles bounce upon the bottom of the disengager vessel or uponearlier disengaged particles of solids which are retained upon or aremoving across the bottom surface. Since the height of rise, that is, thedisengaging height, of catalyst within a disengager is generally quitehigh, the disengaged particles may have ya considerable distance of freefall. Unless provision is made for arresting or minimizing suchfreefall, severe attrition of the solid particles may result.

It is a principal object of the present invention to provide adisengager adapted to receive in the peripheral region thereof aplurality of upwardly discharging streams of solids and lift gas, and toso direct or deflect the rising solids that forceful impingement ofparticles against the structural surfaces and forceful`particle-to-particle contact between the solids will be held `to aminimum, with resultant decrease in solids attrition.

l, In accordance withthe invention, the lift pipes enter through thelower end of the disengager at points distributed along and adjacent tothe inner periphery of the vessel. The lift pipes may enter eithervertically or at a slight inclination toward the axis of the vessel. Theopenings in the bottom of the disengager for receiving the lift pipesare ofgreater diameter than the lift pipes and are provided with shortcylindrical guide sleeves into which the lift pipes extend. The liftpipes are free to move longitudinally within the sleeves to accommodateexpansion or contraction of the pipes resulting from ternperaturechanges.

Each guide sleeve has a solids-deflecting hood attached to its upperend. The lower portion of the hood forms a vertical tubular extension ofthe guide sleeve and, by reason of the increased flow area, providessome additional decelerating effect for the solids which, preferably,

`2,873,146 Patented Feb. 10, 1959 have already been decelerated in theupper end region of the lift pipe. The remaining upper portion of thehood is half cut away on the side toward the axis of the vessel, thevertical sides of the half section being equally extended by flatparallel vanes toward `the central region of the vessel. Thus, the openportion of the hood surrounds the rising stream of solids on threesides, The hood extends upwardly to the highest practical level withinthe disengager, and the upper end of the hood is turned inwardly towardthe axis of the vessel.

An inverted dished baille is supported horizontally above the circularrow of hoods and outwardly overhangs the same. The baille is verticallyspaced from a central lift gas outlet at the top of the vessel, so thatthe rising lift gas follows a tortuous path, rst flowing upwardly andinwardly from the hoods toward the axis of the vessel, and then in adouble reversal of flow outwardly over the tops of the hoods andinwardly over the top of the dished bale to the gas outlet.

In the lower central region of the disengager vessel a dished receptacleor tray having a plurality of short drain pipes is rigidly positioned ata level just below the side discharge openings of the hoods. Thedisengaged solids fall onto the surface of the central dished head anddrain freely through the short drain pipes, again falling freely to thebottom of the disengager vessel. Elongated draw- .oif pipes distributedabout the bottom of the vessel conduct the disengaged solids by freefall to a surge chamber, not shown, which is located below thedisengager vessel and from which the solids may be returned to theconversion system.

For a fuller understanding of the invention reference may be had to theaccompanying drawings forming a part of this application, in which:

Fig. 1 is a sectional elevation of the lift disengager;

Fig.` 2 is a sectional plan View taken along the line of 2 2 of Fig. l;

Fig. 3 is a fragmentary section `of a group of hoods; and t Fig. 4 isaplan View of twoadjacent hoods.

Referring toFig. l of the drawings, the disengager is of the bottomportion of the lift has been omitted for the sake of clarity, since theyform no part lof the presentinvention.

The disengager receives through its lower end theupper ends of alcircular row of lift pipes 14. Ten lift pipes have been illustratedinthe drawing, but fewer or more lift pipesmay be employed, as desired.The disengager is rigidly supported above the upper end of the`hydrocarbon unit, as shown, as by a lower extension 15 of thecylindrical shell 11, `or by other suitable structural elements.

In the illustrated embodiment the lift pipes 14, which may be assumed tobe upright and straight over the substantial major portion of theirlength, have their upper endsinclined slightly inward toward the axis of`the disengager. At each point where a lift pipe enters the lower endofthe disengager a guide sleeve 16 of larger diameter than the lift pipeis set in suitable openings inthe bottom of the head 13 to freelyreceive the upper end of the lift pipe. Radial spacers 17 are securedabout the upper end of the lift pipe to freely guide `and to maintainconcen` tricity of the lift pipeI `within the sleeve during longitudinalmovement of the lift pipe as a result of expansion or contraction withchanging temperature. The sleeve ast/3,146

guide 16is; set at( the same angle as the lift pipe 14 and has attached,as by butt welding, to its upper end a solids-deliecting hood, generallyindicated by the numeral 18.

The hood 1d comprises a lower cylindrical portion 19- ofthe samediametery as guide sleeve 1'6. The semi-cylindrical portion of cylinder19 located farthest from the axis of the disengager has a verticalextension 21 extending upwardly. toa level near the top of thecylindrical portion 11 and is cut ofi at an angle, as shown at 22.

Elongated V-shaped channel members 23, of the same length as verticalextension` 21, are set vertically between adjacent extensions 21, withythe base, of each channel pointing toward the axis of the disengager.The vertically-positioned edges of each V-channel are attached to theadjacent vertical edges of adjacent extensions 21. The arrangement issuch that the sides of channels 23 forming a radial pair of Vanes foreach extension 21 are Y substantiallyI parallel. Obviously, with a`lesser number of lift pipes itmay become impracticable tol employV-channels to form the parallel vanes, in which case they may befabricated at a U-channel or even asV separateplate elements.

An inclined baie plate 24 is attached near the upper en d of each hood1S so as to deflect high-rising solid particles toward the axial regionof the disengager. The top surface of the inclined baffle 24 togetherwith they upper end portions of members'21 and 23 forms a catchbasin forstray particles. A drain hole. 25 in the side of extension 21 permitssolids to drainA from the catch-basin and fall to the bottom of thevessel.

An inverted, dished baie 25 ispositioned in the upper central region ofthe vessel and overhangs the circular row of hoods 18, the batlie beingsupported from the upper ends of the hoods, as by vertical supportmembersl 27. Bailiel 26- is spaced from upper head 12 of the disengagervessel so that the lift gas, free of solids, may flow from the upperperipheral region of the disengager through annular gap 28 and then overthe top of baffle 26 into and through the central outlet 29 at the topof the vessel. Depending from the central portion of the bafe 26 is anelongated pipe member 31 having a plurality of longitudinal ns 32extending radially outward. The number of tins 32 corresponds to thenumber of hoods 18, the iins being directed toward the apexes of theV-channels 23.

A hanged, dished` head comprising a tray portion 33 and a vertical sideor flange portion 34 is positioned in the lower central region of thedisengager, inwardly of the lower cylindrical portions 19 of the hoods18. A plurality of vertical spacers 35 are attached along one edge tothe cylindrical. portions 19 and along the upper portion of theiropposite edge to the vertical flange 34 of the receptacle 33 so as tounite the whole into a rigid unitary structure supported from the guidesleeves 16. rl`he bottomA of the receptacle formed by members 33 and 34is provided with a plurality of short drain pipes 36, so thatdisengaged. solids falling upon the tray may be temporarily interruptedin their fall and then fall freely through the pipes 36 tothe bottomofthe disengager vessel.

The bottom of thel disengager vessel is provided with elongated draw-olfpipes 37 through which solids collected at the bottom of the disengageron lower dished head 13l may fallV freely to a receiving vessel orchamber located below the disengager, but not shown in the drawing.Suchl lower receiving vessel may provide the storage or' surge for thesolids circulating system.

In the operation of the invention, the streams of lift gasand solidsdischarging from liftpipes 14 and passing through guide sleeves 16 and`cylindrical portions 19 are deected slightly toward the axis of thedisengager as they traverse the elongated open portions of the hoodsprovided by members 21 and 23. Such portion of the solids as may rise tothe top ofthe hood is deflected by the inclined baiile 24 into the massof solids moving inwardly and upwardly toward the axial region of the.disengager. Within such axial region the solid particles becomedisengaged from the lift gas and reverse their direction of flow so asto fall freely toward the bottom of the disengager. Some portion of theinwardly moving mass of deflected solids will have sucient energy toreach the finned tube 31 depending axially from the baiiie 26. Thefinned tube 31- arrests the further inward movement of the particles andthey are caused to either rebound or fall downwardly toward thereceptacle, or tray 33 located some distance below. It is expected thatto a great extent the vertical side members 23 which channel the flow ofsolids` inwardly toward the axis of the disengager, together with thefins 32 of the depending member 31 will cause the solids dischargingfrom the plurality of lift pipes to be distributed substantiallyuniformly throughout the actual region of disengagement, so that thedisengaged solids will descend in a substantially uniform pattern uponthe surface of tray 33.

Obviously, withv particles of solids traveling at high velocity andbombarding all exposed` portions of thestructural members as well ascolliding with each other, it is inevitable that some of the particlesWill be deliected over the tops of the hoods and move toward the annularspace 28 through which the lift gas is rising to reach the centraloutlet 29. The velocity of the lift gas flowing over the region abovethe hoods is below supporting velocity for the solid particles, so thatthe stray particles readily disengage themselves from the lift gas` andfall either into the catch basins formed on top of the inclined baflles2,4, or pass over the catch basins and fall tothe bottom of thedisengager through the spaces between the vessel wall 11 and the outersurfaces of members 21, 19 and 2,3.

The receptacle or tray 33 arrests the free fall of the disengaged solidsbefore they have attained any substantial gravitational acceleration. Aportion of the dis engaged solids will collect on the bottom of tray 33and form a stagnant layer surrounding the inlet ends of drain pipes 36.The surface of the layer of solids around each outlet will be inclinedto the horizontal at the angle of repose for the particular solids.Thus, those disengaged solids which do not actually fall directlythrough the drain tubes 36 will land upon the layer of solids supportedon the tray 33 and roll down the inclined surface areas of such layerinto and through the drain tubes 36. Solids discharging from drain tubes36 fall freely to the lower head 13 of the disengager and, in similarmanner, are either retained in part as a stagnant layer at the bottomof. the vessel or roll down the inclinedsurfaces of thestagnant layer ofsolids into and through the draw-oi tubes 37. It is contemplated thatthe substantial major portion of the solids will become disengagedwithin the central region of the disengager and will descend to thebottom of the disengager as just described, and that only a relativelyminor portion of the total disengaged solids will be deilected to theupper peripheral region of the disengager and be caused to` parallel`plate members extending from the vertical sides of the hood openingstoward the central region of the vessel tends to avoid any substantialamount of particleto-particle impact'between the solids of adjacentstreams. Without the physicalV barrier orl baffling provided by thepresent invention all the discharging streams of solids would spread andtend to merge as a broad moving mass of dispersed solids in the upperregion of the disengager, with consequent substantialparticle-to-particle contact with `the rising solids and the fallingdisengaged particles. With the present channeling and inward de flectionof the separate streams the particles, after losing their momentum as aresult of gravitational decelera tion, and after reversing theirdirection of flow, fall` freely downward within the upper central regionof the vessel. Since the substantialmajor portion of the freefallingdisengaged particles descend within the central region ofthe disengager,that is, within the area` surrounded by the envelope of upwardlydischarging streams of solids, there is a minimum of collisions betweenupwardly moving and downwardly moving particles.

In the usual commercial practice lift pipes are tapered, at least alongthe upper end portion,` so as to decelerate the solids before theirdischarge into the disengaging zone, thereby lowering theheightrequirements of the disengager for effecting complete decelerationand disengagement from` the rising lift stream. As the solids dischargeinto the larger guide sleeve and pass through the hood the gas velocityquickly/"diminishes `to such eX- tent that further upward movement ofthe solids is almost entirely the effect of momentum.

Upon discharge into the wider path formed by the guide sleeve and thetubular portion of the hood the solids stream tends to diverge orspread. In passing through the open upper portion of the hood the solidsare free to move gradually inward toward the axis of the disengager inresponse to the horizontal force component. At the opposite side of thesolids stream, however, the solids soon strike the vertical wall of thehood and are deflected inwardly. The cumulative effect of the inwardhorizontal force components of the deflected solids as they colliderepeatedly with solids nearer the center of the solids stream tends toforce the stream out of its vertical path and produces a curvedtrajectory toward the axis of the disengager. To be timely effective,the rising stream of solids should engage the de fleeting surface of thehood along a lower portion thereof. On the other hand, the diameter ofthe hood should be sufficiently larger than the diameter of the liftpipe to effect a desired further reduction in gas velocity.

It is believed that, once the solids leave the top of the lift pipe andthe accompanying lift gases are allowed to expand, first, withintheenlarged flow path provided by members 16 and 19 and, then, within thelarger disengager vessel, the ultimate path of flow which the solidparticles thereafter take is substantially exclusively the result ofcollisions and impacts either between the solids and the structuralsurfaces within the vessel or between the solids. In other words, veryshortly after the solids and gas leave the lift pipe the gas isdecelerated to a velocity much too low to have any significant effectupon the direction of movement of the solid particles. It is partly forthis reason that the channeling or baffling of the separate dischargingstreams of solids effectively reduces the amount of solids attrition.

In order to minimize impact attrition of the solid particles it ispreferred that the sides of thehood which serves to deflect or channelthe flow of solids toward the center of the vessel be designed andlocated in such manner that the widening stream of upwardly movingsolids impacts the hood at a very shallow angle, prefer-V ably less thanabout With respect to the inclined baffle 24 forming the top of eachhood, the angularity of impact may be somewhat greater, because theparticles attaining such height will already have lost much of theirmomentum.

It is the purpose of the hood 18 to surround the rising stream of solidson three sides. The effective length of the deflector hood, that is, theportion formed by elements 21 and 23 should be as long as possible,within practical limits. The hood diameter, however, is prefer,

ably inthe range `of about 1.5 to 2.5 times the lift pipe diameter'.

A further restriction on hood size is recommended, however. Since theinward deflection of the solids stream as a whole commences only afterthe sides of the stream engage the inside wall of the hood, suchengagement should commence at a low level along the opensided portion ofthe hood. If the diameter o f the sleeve extension 19, which also may beconsidered the diameter of the hood, is too great, so that there is aconsiderable horizontal spacing between the lift pipe and the sleeve,the solids will not strike the hood at a level low enough to effect thedesired deflection. It is considered desirable, therefore, that thesolids leaving the lift pipe strike the side ofthe hood at a levelwithin the lowermost 25% of the overall distance between the top of thelift pipe and the top of the hood. This can best be expressed by thefollowing equation:

Dmax: maximum/sleeve diameter, ft.

d==lift pipe diameter at top, ft.

L=blow height above top of lift, ft., blow height being the averagevertical distance from the top of the lift to the turned in top portionof the hood.

In designing a hood for a particular application there is always thenecessity of weighing the value of increased hood height, whereby therewill be substantially no largersize solids hitting the top of the hoodor the dished baffle above it, against the disadvantage of increasingthe height or vertical distance through which the disengaged particlesmust fall to reach the bottom of the disengaging zone. Too great adistance of free fall can cause excessive fracture of the solids as theybounce upon the bottom of the vessel or upon the tray.

It is expected that the principal benefits in the way of reduced solidsattrition will be effected by reason of the fact that there is a minimumof impacts between the falling solids and the rising solids. Once thesolids fall below the zone or region where collision with rising solidsis possible, much of the danger of severe impact is eliminated. The tray33, which lets the falling solids down in easy stages, further reducesthe danger of severe impact. However, in some cases it may be possibleto eliminate the tray 33 and permit the disengaged solids to falldirectly to the bottom of the disengager Without serious danger ofimpact attrition.

While the invention has been shown in but one form, it will be obviousto those skilled in the art that it is susceptible to variousmodifications and improvements without imparting from the spiritthereof, and it is desired therefore that only such limitations shall beplaced thereon as are specifically set forth in the appended claims.

What is claimed is:

l. A solids disengager for a multiple pneumatic lift having a pluralityof lift pipes discharging at uniformly spaced locations in a horizontalcircular row comprising: a disengager vessel adapted to encompass suchdischarge locations at its lower end; guide sleeves set in the bottom ofsaid vessel so as to receive in sliding engagement the discharge ends ofsaid lift pipes, said guide sleeves being of substantially greaterdiameter than said lift pipes; a plurality of solids-deflecting hoodsindividual to and secured to the upper ends of said guide sleeves, saidhoods opening inwardly toward the axis of said vessel along the majorupper portion of their length and i having parallel vertical platemembers extending inwardly toward the axis of said Vessel from thevertical sides of saidopenings and an inclined upper end portionconverging toward said axis, whereby solids discharging upwardly andinwardly from said hoods reverse their direction of flow and descendWholly within the central regionl of said vessel and substantially outof contact with the rising streams of solids; a central lift gas outletat the upper end of' said vessel; a horizontal baille spaced from theupper end of said vessel and overhanging the circular row of hoods,whereby lift gas discharging from said hoods and directed toward theupper central region of said vessel is first deflected outwardly by saidbaie to the peripheral region thereof and then caused to ow upwardly andinwardly over the top of said horizontal baille to said lift gas outlet;and a plurality of solids draw-olf tubes distributed about the lower endof said vessel adapted to drain the disengaged solids by free fall fromsaid vessel.

2. Apparatus as in claim l including a horizontal tray located at anintermediate level within said vessel and below the hood openings, saidtray being arranged to intercept substantially all the solidsdischarging from said hoods and descending by free fall within thecentral region of said vessel; and a plurality of drains in the bottomof said tray adapted to drain the intercepted solid particles by freefallfrom said tray to the bottom of said vessel.

3. Apparatus as in claim l including an elongated baffle dependingaxially from the center of said horizontal baille and comprising acylindrical member having longitudinal ins extending, radially outward'therefrom and corresponding in number to the number of said liftpipesQsaid radial fins being directed equi-distantly between said liftplpes- .,o

4. Apparatus as in claim l in which the curved portions of said hoodsform vertical extensions of the outer half of their associated guidesleeves, and in which the diameter of said guide sleeves is in the rangeof about 1.5v to 2.5 times the diameter of said lift pipes.

5. Apparatus as in claim l inV which the diameter. of the confined pathformed by said guide sleeve and the lower portion of its associatedhoodis expressed by the equation f DmBX= 1/z L tan 11"-l-d where iDmax=maximum sleeve diameter, ft. d=lift pipe diameter at top, ft. L-blow height above lift, ft.

whereby the expanding stream of solids meets the side'

